JP7142513B2 - METHOD AND DEVICE FOR PROMOTING VOLUME REDUCTION BY CONTINUOUS WASHING OF CONTAMINATED SAND - Google Patents

Description

The present invention relates to a method and apparatus for promoting volume reduction by continuous washing of contaminated sand, and for example, a method for promoting volume reduction by continuously washing contaminated sand generated during decontamination work. and processing.

Currently, there are soils contaminated with heavy metals such as lead and cadmium, dioxins, and even radioactive substances, and in order to maintain a good environment, it is an urgent task to remove these contaminants. Conventionally, various techniques have been developed for removing contaminants from contaminated soil (see Patent Document 1, for example).

The technology described in Patent Document 1 achieves a high volume reduction rate, makes it possible to automatically operate the classification and washing processes, and further improves the operation efficiency to enable large-scale treatment of contaminated soil. The present invention relates to a volume reduction treatment method. This method for reducing the volume of contaminated soil consists of a step of removing contaminants contained in the contaminated soil (removed soil) to be reduced, A vertical centrifugal classifying dehydrator is used to classify and dehydrate sand, which is the object to be removed, from the contaminated soil (removed soil) from which the gravel has been removed (removed soil). It also includes a step of washing and removing, and a step of dehydrating and removing clay from contaminated soil (removed soil) from which sand has been removed.

The technique described in Patent Document 1 includes four steps as steps for volume reduction treatment of contaminated soil having a particle size of about 75 μm to 2 mm. By peeling off the clay that has adsorbed the contaminants, we are trying to reduce the volume of the contaminants.

In the first step, muddy water containing compressed air and contaminated sand is sprayed in a jet shape to collide with a metal plate, and the soil particles are rubbed and washed by shearing force, and the clay content is peeled off from the surface of the soil particles. It is a process to let

In the second step, by injecting muddy water containing contaminated sand from a venturi tube, air is drawn into the muddy water, passed through a spiral line mixer to generate microbubbles, and soil particles are generated by generating turbulence. This is a step of rubbing and washing each other and preventing re-adhesion of clay to sand due to separation of clay from the surface.

In the third step, the dispersed material is adsorbed on the surface of the soil particles, and the soil particles are repelled by the ionization action on the dispersed soil particles to maintain the separated state of the soil particles, and the clay content is peeled off from the surface of the contaminated sand. , is a step of maintaining the separated state of the clay content.

In the fourth step, radical ions are generated by the generation of microbubbles in the muddy water and the application of high-frequency vibration to the muddy water, and the action of the radical ions decomposes the organic matter present on the surface of the polluted sand, resulting in adsorption of the organic matter. This is the step of separating contaminants present on the contaminated sand surface.

JP 2014-69157 A

However, the above-mentioned conventional technology is a useful technology in that it is possible to efficiently treat a large amount of contaminated soil, but it is difficult to remove the clay content on which contaminants are adsorbed from the surface of contaminated sand4. Since the clay particles with adsorbed contaminants are removed from the contaminated sand surface in one process, the batch processing method must be adopted. Therefore, it is necessary to provide a pseudo-continuous processing method by preparing a plurality of the same apparatuses. Therefore, in cases where a large amount of contaminated sand needs to be reduced in volume, there is a possibility that the equipment will become large.

Further, in the first step and the second step, the volume reduction treatment is performed only after the contaminated sand is supplied to the pump installed at the bottom of the water tank. However, if the agitation force in the water tank is strong, contaminated sand with small particle size will stay in the upper part of the water tank for a long time, so there is a possibility that the processing time will end without passing through the pump even once. I can't say no.

Furthermore, it is conceivable that the Venturi tube and the spiral line mixer may be worn out by the contaminated sand, and the high-frequency vibrator may break down, so maintenance may be troublesome.

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned circumstances. It is an object of the present invention to provide a method and an apparatus for promoting volume reduction by continuous washing treatment of polluted sand, which can reduce the volume by exfoliating clay.

The method and apparatus for promoting volume reduction by continuous washing treatment of contaminated sand according to the present invention have the following features in order to achieve the above-mentioned objects. That is, the method for accelerating volume reduction by continuous washing treatment of contaminated sand according to the present invention is to mix contaminated sand with clay adhering to washing water with agitating blades or an underwater mixer in a mixing agitating water tank, thereby making the specific gravity uniform. and a mixture of washing water and contaminated sand whose specific gravity has been made uniform by the mixing and stirring step is sucked, jetted together with compressed air, and collided with a plate-shaped member to cause contamination. and a clay stripping step for stripping clay from sand . Then, a mixing stirring device used in the mixing stirring step and a clay separation device used in the clay separation step are set as a set of device groups, and by providing a plurality of sets of the device group, the mixing stirring step and the clay separation are performed in multiple stages. A peeling process is carried out.

In addition, the collision jet water tank constitutes a set of equipment group for performing the mixing and stirring process and the clay separation process, and in the mixing and stirring process and the clay separation process performed in multiple stages, the final stage of the stirring and mixing process by the collision jet water tank. Contaminated sand and washing water after cleaning in the viscosity removal process are circulated to the agitation mixing process and the viscosity removal process by the collision jet water tank at the foremost stage, and the contaminated sand can be continuously washed. is.

The apparatus for promoting volume reduction by continuous washing treatment of contaminated sand according to the present invention mixes contaminated sand with clay adhering to washing water with agitating blades or an underwater mixer in a mixing agitating water tank, thereby making the specific gravity uniform. a mixing agitating device that generates a mixed mixture, and a mixture of washing water and contaminated sand whose specific gravity has been made uniform by the mixing and agitating device, is sucked in, jetted together with compressed air, and made to collide with a plate-like member to remove the contaminated sand. A set of device groups is constituted by a clay-separating device for separating clay content, and a plurality of sets of the device groups are provided and installed so as to form a plurality of stages . In the multi-stage apparatus group, the contaminated sand and washing water that have been washed in the preceding apparatus group are sent to the next-stage apparatus group to continuously wash the contaminated sand.

In addition, the collision jet water tank constitutes a set of equipment group consisting of a mixing agitating device and a clay separation device. It is possible to circulate the washing water to the collision jet water tank at the foremost stage to continuously wash the contaminated sand.

According to the method and apparatus for promoting volume reduction by continuous washing treatment of contaminated sand according to the present invention, the most cost-effective apparatus configuration for volume reduction treatment of contaminated sand in the conventional volume reduction treatment of contaminated soil is adopted. As a result, the contaminated sand is continuously washed and volume-reduced with this device configuration, which not only simplifies the device configuration, but also makes it possible to reliably separate the clay from the contaminated sand, thereby promoting volume reduction. be done.

FIG. 1 is a schematic diagram of a volume reduction promoting device for continuous cleaning treatment of contaminated sand according to an embodiment of the present invention. 4 is a flow chart of a method for promoting volume reduction by continuous cleaning treatment of contaminated sand according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a clay-part removal device used in a volume reduction promoting device for continuous cleaning treatment of contaminated sand according to an embodiment of the present invention.

Hereinafter, with reference to the drawings, a volume reduction promotion method and a volume reduction promotion device by continuous cleaning treatment of contaminated sand according to an embodiment of the present invention (hereinafter referred to as volume reduction promotion method and volume reduction promotion device). explain. 1 to 3 illustrate a volume reduction promotion method and a volume reduction promotion device according to an embodiment of the present invention. FIG. 1 is a schematic diagram of the volume reduction promotion device, and FIG. 2 is a volume reduction promotion method. , and FIG. 3 is a schematic diagram of the clay component removal apparatus.

<Overview of volume reduction promotion method and volume reduction promotion device>
In the volume reduction acceleration method and volume reduction acceleration device according to the embodiment of the present invention, contaminated sand with clay adhering thereto and washing water are mixed and agitated to make the specific gravity uniform, and then the mixture is compressed with compressed air. It is characterized in that the process of exfoliating the clay from the contaminated sand by spraying it in jet form and colliding with the plate-shaped member is repeated. In the present invention, contaminated sand is soil to which clay containing contaminants is attached, and grains of 0.075 to 2 mm in the "Engineering Classification Method for Geotechnical Materials (Geotechnical Society Standard: JGS 0051)" It is intended to include not only fine, medium and coarse sand with a diameter, but also pebbles of sizes falling within the scope of fine pebbles and pebbles.

<Volume reduction promotion device>
As shown in FIG. 1, the volume reduction acceleration device according to the embodiment of the present invention includes a plurality of groups of devices each including a mixing/stirring device 10 and a clay separation device 20 as one device group. Each set of equipment groups is installed in a plurality of stages in order to continuously perform the cleaning treatment of the mixture of contaminated sand and cleaning water.

Contaminated sand and washing water that have been washed in the preceding equipment group are sent to the next equipment group for continuous washing treatment. The device group at the first stage consists of a mixing/stirring water tank 30 in which the mixing/stirring device 10 is installed and a collision jet water tank 40 in which the clay separation device 20 is installed. Then, by installing the mixing agitating device 10 in the collision jet water tank 40 and sending the mixture to the collision jet water tank 40 installed in the next stage, a group of devices in the second and subsequent stages is constructed. Further, by circulating the mixture of contaminated sand and washing water in a plurality of groups of devices, the size of the device can be reduced.

<Mixing stirrer>
The mixing agitating device 10 (the agitating blade 11, the agitating motor 12, and the rotary shaft 13) mixes and agitates the contaminated sand with clay adhering thereto and the washing water, thereby producing a mixture having a uniform specific gravity. device. In this embodiment, the mixing/stirring water tank 30 and its accompanying devices and the collision jet water tank 40 and its accompanying devices function as the mixing/stirring device 10 . If there is a risk of clay clumps being mixed in with the contaminated sand to be washed, crush the clay clumps by using a crusher such as Oniba roll or roll press alone or in combination, and then use a submersible mixer or sand pump. Equipment for disintegrating the crushed clay is used alone or in combination.

<Mixing agitation water tank>
The mixing and agitating water tank 30 is filled with contaminated sand conveyed by a conveying device 50 such as a belt conveyor, and mixed and agitated with washing water by the agitating blade 11 or an underwater mixer (not shown), so that the specific gravity is uniform. It is a water tank for generating a mixture of Therefore, in the first stage of the cleaning treatment process, the mixing and stirring water tank 30 and the accompanying stirring blades 11, stirring motor 12, and rotating shaft 13 function as the mixing and stirring device 10. FIG. Note that the mixing and stirring device 10 may use an underwater mixer instead of the stirring blade 11, the stirring motor 12 and the stirring shaft 13.

<Collision jet water tank>
The collision jet water tank 40 is a water tank for recovering a mixture of washing sand and washing water after the treatment of removing clay from contaminated sand. In addition, the collision jet water tank 40 also has the function of stirring the mixture of contaminated sand and washing water from which the clay has been removed by means of the stirring blade 11 or an underwater mixer (not shown) to make the specific gravity of the mixture uniform. I have. Therefore, in the second and subsequent stages of the cleaning treatment process, the collision jet water tank 40 and the accompanying stirring blades 11, stirring motor 12, and rotary shaft 13 function as the mixing and stirring device 10. FIG.

The stirring blade 11 is attached to the lower end of the rotating shaft 13 of the stirring motor 12 . Further, the shape of the stirring blade 11 is not limited to the illustrated V-shaped one, and a plurality of I-shaped stirring blades may be installed. The agitating blade 11 is designed to prevent the contaminant sand deposited at the bottom of the mixing agitating water tank 30 and the collision jet water tank 40 from arching and clogging the outlets provided at the lower ends of the mixing agitating water tank 30 and the collision jet water tank 40. It has a function to prevent the water from entering and a function to agitate the mixture of cleaning sand and cleaning water in the mixed agitating water tank 30 and the collision jet water tank 40 . A water level sensor (not shown) for measuring the water level of the mixture of cleaning sand and cleaning water is provided in the mixing water tank 30 and the collision jet water tank 40. When the water level sensor detects a predetermined water level, the following A suction device (sand pump) 21 may be operated to deliver a mixture of cleaning sand and cleaning water to the collision jet water tanks 40 of the stages.

<Clay peeling device>
The clay stripping device 20 sucks the mixture of washing water and contaminated sand whose specific gravity has been made uniform by the mixing and stirring device 10, and jets the mixture together with compressed air in the form of a jet to collide with the plate-like member 24 to separate the clay from the contaminated sand. It is a device for exfoliating skin. As described above, the clay separation device 20 is installed in the collision jet water tank 40 . Note that the clay separation device 20 may be provided inside the collision jet water tank 40 or may be provided above the collision jet water tank 40 . Moreover, the number of the clay component peeling devices 20 in each stage is not limited to one, and a plurality of devices may be provided.

FIG. 3 shows an example in which the clay stripping device 20 is provided above the collision jet water tank 40 . As shown in FIG. 3, in the upper part of the collision jet water tank 40, there is provided a housing portion 41 with an open bottom. 22, an injection device (injection nozzle) 23, and a plate member (iron plate) 24 are installed. A suction device (sand pump) 21 is connected to the compressed air supply device 22 and the injection device (injection nozzle) 23 . The storage unit 41 is a device for preventing a mixture of contaminated sand and cleaning water from scattering outside the collision jet water tank 40 .

The clay stripping device 20 includes a suction device 21 such as a sand pump for sucking the mixture of contaminated sand and washing water, a compressed air supply device 22, and a jet of the mixture of contaminated sand and washing water. It is equipped with a device (injection nozzle) 23 and a plate-like member (iron plate) 24 that collides with a mixture of contaminated sand and cleaning water jetted together with compressed air. Then, a mixture of contaminated sand and washing water is sucked by the suction device 21 and jetted from the jetting device (jetting nozzle) 23 together with compressed air in a jet shape to collide with the plate-like member 24, so that the soil particles are separated by shear force. It is possible to remove the clay content from the surface of the soil particles while rubbing the soil. In the example shown in FIG. 3, an iron plate serves as the plate-like member 24, but when the clay separation device 20 is provided inside the collision jet water tank 40, the inner wall of the collision jet water tank 40 serves as the plate-like member 24.

<Continuous cleaning process using multiple device groups>
The volume reduction promotion device according to the embodiment of the present invention includes a mixing/agitation water tank 30 and collision jet water tanks 40 provided in a plurality of stages. do. The number of installed collision jet water tanks 40 is appropriately set according to the type and degree of contamination. Moreover, it is preferable to set the capacities of the mixed stirring water tank 30 and the collision jet water tank 40 so that the retention time of the mixture of the contaminated sand to be washed and the washing water is about 5 minutes.

In addition, when it is necessary to reduce the size of the treatment equipment due to restrictions on the place where the treatment equipment is installed, etc., the contaminated sand is transferred from the collision jet water tank 40 provided at the final stage to the collision jet water tank 40 at the first stage. Circulate the water mixture.

<Volume reduction promotion method>
As shown in FIG. 2, the method for promoting volume reduction according to the embodiment of the present invention includes the mixing and stirring step (S1) and the clay separation step (S2) as a set of washing treatment steps. It is designed to be repeated multiple times. That is, the next step of mixing and stirring (S1) and the next step of removing clay (S2) are repeatedly performed on the contaminated sand and washing water from which the clay has been removed in the step of removing clay (S2). Contaminated sand is continuously washed by this method. In this case, the washing treatment step may be a step of circulating a mixture of contaminated sand and washing water. In addition, as a step of judging the end of the cleaning process, the adhesion state of clay (residual degree, radiation concentration, etc.) is measured for the washed sand that has undergone the clay separation step (S2), and the adhesion state of clay (residual degree, radiation density, etc.) becomes equal to or less than a predetermined threshold value (S3), the cleaning process is terminated.

Since it is not possible to determine the adherence state of the clay content in real time, it is usually determined whether to reprocess or terminate the cleaning process after waiting for the analysis results. In addition, if the contaminated object is a radioactive substance, the concentration of radioactivity is measured with a radioactivity concentration meter (NaI scintillation detector, etc.) when transferring the cleaning sand on the belt conveyor, and the measurement result of the radioactivity concentration is Accordingly, a sorting belt conveyor or the like is used to separate the contaminated sand to be reprocessed from the contaminated sand to be cleaned. In the case of heavy metals, the results of rapid analysis and process analysis are awaited before deciding whether to end the cleaning process.

<Mixing and stirring step>
The mixing and agitating step is a step for producing a mixture having a uniform specific gravity by mixing and agitating contaminated sand to which clay is adhered and washing water. This stirring and mixing process is performed in the mixing stirring water tank 30 or the collision jet water tank 40 .

<Clay separation step>
In the clay exfoliation process, a mixture of washing water and contaminated sand whose specific gravity has become uniform in the mixing and agitation process is sucked and jetted together with compressed air by a compressed air supply device 22 and an injection device (injection nozzle) 23. This is a process for stripping the clay content from the contaminated sand by colliding with the plate-like member 24 . This clay removing step is performed in the clay removing device 20 provided in the collision jet water tank 40 .

<Repeated implementation of the cleaning process>
The repeated implementation of the cleaning treatment process will be specifically described. Contaminated sand conveyed by a conveying device 50 such as a belt conveyor is put into a mixing/stirring water tank 30, mixed with washing water, and stirred to produce a mixture having a uniform specific gravity. Then, the mixture of washing water and contaminated sand with a uniform specific gravity is sucked by a suction device 21 such as a sand pump, and in a collision jet water tank 40 using a compressed air supply device 22 and an injection device (injection nozzle) 23, It is jetted together with compressed air and collides with the plate-like member 24 to separate the clay from the polluted sand.

Subsequently, in the collision jet water tank 40, the contaminated sand and the washing water are stirred by the mixing and stirring device 10 including the stirring blades 11 and the underwater mixer so that the specific gravity of the mixture of the contaminated sand and the wash water becomes uniform. Then, a mixture of contaminated sand and washing water whose muddy water specific gravity has become uniform is sucked by a suction device 21 such as a sand pump and guided to the collision jet water tank 40 in the next stage, where it is supplied to a compressed air supply device 22 and an injection device (injection nozzle). 23 is used to separate the clay from the contaminated sand by injecting it in a jet shape together with compressed air and making it collide with the plate-like member 24 .

Then, in the collision jet water tanks 40 installed in the next and subsequent stages, the above-described clay removal process and mixing and stirring process of contaminated sand and cleaning water are repeated (continuous cleaning process). Further, in the case of reducing the scale of the facility, by circulating the mixture of contaminated sand and washing water after washing treatment in the final-stage collision-jet water tank 40 to the first-stage collision-jet water tank 40, the above-described continuous Repeat the washing process.

Then, when it is judged that the clay content has been sufficiently removed from the contaminated sand (the concentration of radioactivity, etc. has fallen below the allowable value), the mixture of contaminated sand and washing water is taken out, the continuous washing process is completed, and the next stage of processing is performed. , Contaminant separation treatment (cyclone treatment) and dehydration treatment using a dehydration treatment device such as a filter press are carried out to reduce the volume of contaminated soil (contaminated sand).

<Advantageous effect compared with conventional technology>
The contaminated sand volume reduction promotion method and volume reduction promotion device according to the present invention have the following advantageous effects as compared with the prior art.
(1) It is possible to prevent the risk of generating contaminated sand that has never been washed.
(2) The quality control of the cleaning process can be controlled by the number of installed collision jet water tanks 40 .
(3) Since continuous treatment is possible, it is possible to reduce the installation cost (including the radiation protection tent facility) and the installation area of the facility by significantly miniaturizing the facility.
(4) If the cleaning process is not sufficiently performed, the contaminated sand can be resupplied (circulated) to the facility, thereby surely satisfying the cleaning target.
(5) Treatment costs can be reduced because the equipment required for the cleaning treatment and the volume reduction treatment can be greatly simplified.

REFERENCE SIGNS LIST 10 mixing stirring device 11 stirring blade 12 stirring motor 13 rotating shaft 20 clay peeling device 21 suction device (sand pump)
22 Compressed air supply device 23 Injection device 24 Plate member 30 Mixing stirring water tank 40 Collision jet water tank 41 Storage unit 50 Conveying device (belt conveyor)

Claims (4)

a mixing and agitating step of generating a mixture having a uniform specific gravity by mixing contaminated sand with clay adhering thereto and washing water with agitating blades or an underwater mixer in a mixing agitating water tank ;
A clay stripping step in which the mixture of washing water and contaminated sand whose specific gravity has become uniform in the mixing and stirring step is sucked, jetted together with compressed air, and collided with a plate-shaped member to strip the clay from the contaminated sand. When,
including
The mixing and stirring device used in the mixing and stirring step and the clay separation device used in the clay separation step are set as one set of device groups, and by providing a plurality of sets of the device group, the mixing and stirring step and the clay separation are performed in multiple stages. performing a stripping step;
A method for promoting volume reduction by continuous washing treatment of contaminated sand, characterized by: The collision jet water tank constitutes a set of equipment groups for performing the mixing and stirring process and the clay separation process, and in the mixing and stirring process and the clay separation process performed in the plurality of stages, the stirring and mixing process by the collision jet water tank at the final stage and Contaminated sand and washing water after cleaning in the viscosity stripping process are circulated to the stirring and mixing process and the viscosity stripping process by the collision jet water tank at the foremost stage, and the contaminated sand is continuously cleaned.
The method for promoting volume reduction by continuous washing treatment of contaminated sand according to claim 1, characterized in that: a mixing agitating device for producing a mixture having a uniform specific gravity by mixing contaminated sand with clay adhering to it and washing water with agitating blades or an underwater mixer in a mixing agitating water tank ;
The mixture of washing water and contaminated sand whose specific gravity has been made uniform by the mixing and agitating device is sucked in, and jetted together with compressed air in the form of a jet to collide with a plate-shaped member to separate the clay from the contaminated sand. When,
Construct a set of equipment groups by
A plurality of the device groups are provided and installed in a plurality of stages,
In the multi-stage device group, the contaminated sand and washing water after being washed in the preceding device group are sent to the next-stage device group to continuously wash the contaminated sand.
A device for promoting volume reduction by continuous washing treatment of contaminated sand, characterized by: The collision jet water tank constitutes a set of equipment group consisting of a mixing agitating device and a clay separation device. Water is circulated to the collision jet water tank at the foremost stage to continuously wash contaminated sand.
4. The apparatus for promoting volume reduction by continuous washing treatment of contaminated sand according to claim 3, characterized in that:

Images